Weird window mode when session falls asleep

[PhilD]

I tend to often have two LOL sessions, in windowed mode, open at the same time: one monitoring the lobby, and the other playing solo games.

If I leave my PC unattended for some time and I come back to the login screen (this is Windows XP), something weird often happens; most of the time, LOL seems to have switched to full screen mode, and if there are two instances, sometimes they seem to "fight" for control of the screen and I can't do a thing about it except reset the computer. And most of the time, the window size for my browser (Firefox) also has been changed. Pretty weird, and a bit annoying.